The present invention relates to printing systems, and more particularly to an improved apparatus and method for transferring an article from one conveyor to another.
Doffing of articles (such as textiles, plastic sheets or the like) is commonly accomplished by a revolving cylinder covered circumferentially with needle tape, positioned in close proximity to a printing blanket, and driven clockwise against the same speed, clockwise rotation of the blanket. The objective is to strip articles from the printing blanket and transfer them to a conveyorized belt for subsequent stage(s) of printing operations, e.g., a drying system.
While needle tape has been found relatively useful in grabbing articles, and pulling them from the blanket, it tends to hold onto the articles when their release is desired, for example, when transferring articles to the conveyor belt. This has caused portions of the articles to turn over, bunch or roll up. As a result, wet printed images on the articles have been damaged and frequent work stoppages required, hindering subsequent operations of the printing system.
In addition, the same speed operation (fixed R.P.M. ratios) of the conveyor belt and blanket have been found to not only inhibit smooth transfer, but also produce inconsistent images with variations in weight, orientation, shape or fiber content of the articles, and with changes in ink, adhesive or tack.